A day after an at-times heated debate on the economy, Tom Mulcair and Justin Trudeau were criticizing Stephen Harper for his use of the phrase 鈥渙ld stock Canadians鈥 during an exchange on refugee policy.

During a major party leaders鈥 debate on the economy Thursday night, Harper came under fire on social media when he responded to a suggestion that Conservative policy strips refugees of some health care benefits.

Harper defended his party saying, 鈥淲e do not offer them a better health plan than the ordinary Canadian can receive. That鈥檚 something new and existing and old stock Canadians agree with.鈥

At a campaign appearance in Calgary Friday morning, a reporter asked Harper what he meant by the phrase.

After reiterating his party鈥檚 stance on health care for refugees, Harper said, 鈥淚t鈥檚 supported by Canadians who are themselves immigrants, and also supported by the rest of us 鈥 by Canadians who have been the descendants of immigrants for one or more generations.鈥

The claws quickly came out on social media when Harper initially made the remark, with many expressing displeasure 鈥 and confusion -- with the Conservative leader鈥檚 apparent categorization of Canadian citizens.

On Friday, Justin Trudeau鈥檚 campaign team said the Liberal leader didn鈥檛 respond to the 鈥渙ld stock鈥 remark during the debate because he didn鈥檛 hear it.

But at a rally in Montreal Friday afternoon, Trudeau said the comment showed that Harper was 鈥渆ager to use the politics of division鈥 during the election campaign.

鈥淭he fact is, Mr. Harper is yet again highlighting that he doesn鈥檛 believe that a Canadian is a Canadian is a Canadian,鈥 Trudeau said.

Mulcair also weighed in on the matter at a campaign stop in Regina Friday afternoon, saying Harper used 鈥渧ery divisive鈥 language.

鈥淚 think we鈥檙e all Canadians and I don鈥檛 like dividing people into categories like that,鈥 Mulcair said.

Social media takes notice

Twitter activity spiked Thursday night following Harper鈥檚 comments:

Post-debate, Google Canada also reported an increase in searches for 鈥淥ld Stock Canadians.鈥